They (the Kurds) never were America's allies ... they fought with the Americans for self-preservation reasons.
I posted the following in another thread:
They had to ... they were almost overrun by ISIS. Had it not been for the US operating in the Kurds' vicinity because of ISIS, they would have been long gone ... and not just the fighters and any male civilian, but also the women and children.
ISIS had moved into the Kurds' territory.
By 2 October 2014, ISIL succeeded in capturing 350 Kurdish villages and towns within the vicinity of Kobanê,[70] generating a wave of some 300,000 displaced Kurds, who fled across the border into Turkey's Şanlıurfa Province.[71] By January 2015, this had risen to 400,000.[66] The Kurdish People's Protection Units (YPG) backed by Euphrates Volcano joint operations room, some Free Syrian Army (FSA) reinforcements, heavily armed Peshmerga of the Kurdistan Regional Government, and American and US-allied Arab militaries' airstrikes began to recapture Kobane.
ISIS laid siege to Kobani/Kobane. Had it not been for US air strikes, because we operated in that area, that large city too would have fallen under ISIS control.
In 2015 the US decided to arm and train the Kurdish fighters, who consisted of a gazillion factions, to defeat a common enemy: ISIS.
That enemy is defeated, the battle has been won; but some of those Kurdish factions are also enemies to a NATO partner ... and we sure as hell don't need a war with a NATO partner.